Re: dwarfs
Well, Dave, most got off the subject and forgot about your questions. I
don't have time to cover it completely, but will try to fill in a little
background.
Miniature Dwarf Bearded (MDB) irises (8 inches and under) include several
species with varying chromosome patterns (some diploids and some
tetraploids). The species most grown is I. pumila with four sets of 8
chromosomes. However, pure I. pumila grows best in colder climates. It is
native to lower parts of mountain ranges in eastern Europe and western
Russia.
Standard Dwarf Bearded (SDB) irises (8 to 16 inches) do include a few
species, but what you will mostly find are derivatives of Tall Bearded X I.
pumila. This makes them have two sets of 8 and 2 sets of 12 chromosomes, a
total of 40. These hybrids are quite fertile for the most part and have been
interbred for many generations to obtain new forms and colors. Now, if you
cross the SDBs back with I. pumila, you will get 8/8/8/12=36. These may be
in the height range of either MDBs or SDBs and many are still fertile.
Intermediate Bearded (IB) irises (16 to 27.5 inches) may be from crosses of
I. aphylla by TBs, but most modern varieties are crosses of SDBs with TBs.
This makes them 8/12/12/12=44. There have been some fertility problems with
this class, but many newer varieties are being crossed. Sometimes SDBs are
crossed with IBs and height may vary between SDB size and IB size and have
uneven chromosome counts.
Because of the wide range of possibilities in these classes, they are
becoming very popular with hybridizers.
Dorothy Willott in Northern Ohio, Zones 5/6
---------------------------------------------------------------------
To sign-off this list, send email to majordomo@hort.net with the
message text UNSUBSCRIBE IRIS
